There is unequivocal evidence from biochemistry and physiology that the diffusible second messenger 3'- 5'cyclic adenosine monophosphate (cAMP) is involved in taste transduction. In contrast, recent reports have emphasized the role of Ca2+ signaling in taste transduction (i.e. Receptor --> G protein --> PLCbeta2 --> delta[Ca2+]i). The significance of the original cAMP data is presently unresolved. The goal of my research is to re-investigate cAMP in taste transduction in the light of current understanding. I propose to image real-time changes in intracellular cAMP using novel, genetically-encoded cAMP reporters. These FRET-based reporters permit one to measure single-cell cAMP levels with excellent spatial and temporal resolution. This work will help define taste signaling at the single cell level and enhance our understanding of how gustatory information is processed and coded within taste buds. Specifically, I postulate that cAMP levels in subsets of individual taste receptor cells are altered in response to gustatory stimuli and that cAMP changes are mutually interactive with Ca2+ fluctuations.